Timepieces having a mechanical movement, including mechanical wristwatches, are often equipped with a number of functions, in particular where fine watchmaking pieces are concerned, and thus normally has a control device having three positions, corresponding for example to the winding of the watch, the fast correction of the date, and the setting of the time, thus requiring a coupling in order to attribute the different functions to the corresponding positions of the control device. The conventional coupling used in this case consists of a corrector yoke controlled by a control stem and displaceable by a pivot motion over a short distance that amounts to a translation. The yoke comprises a mounted coupling and setting wheel adapted to mesh with, respectively be disconnected from a corrector wheel, depending on the position of the yoke. The coupling by translation, however, has the disadvantage that it may induce, in some circumstances, a parasitic rotation of the corrector wheel associated with the displacement of the mounted setting wheel along the circumference of this corrector wheel. This may produce, for example, a slight jump, forwards or backwards, of the minutes hand when the user of the timepiece pushes the control stem after having set the time, which is clearly an inconvenience. In addition, this type of coupling takes up a fair amount of space and therefore is not suitable for use in extra-flat movements. An additional feature, with which numerous timepieces are provided, consists of a chronograph mechanism. This feature also requires a coupling, the conventional coupling mechanism used for this application likewise being based on a movement equivalent to a translation of a mounted coupling and setting wheel. In this case the translation of the mounted coupling and setting wheel produces the start, respectively the stopping of the measurement of the measured time by establishing, respectively by interrupting the kinematic connection between the geartrain of the movement of the timepiece and the chronograph train. This, however, brings problems due to the fact that, as in the case described above of setting the time, the translation of the mounted coupling and setting wheel can, in some circumstances, cause a parasitic rotation of the chronograph train and, consequently, a jump forward of the chronograph hand. Although this does not influence the reading of the measured time because the gear play is made up subsequently, it is an aesthetical problem at the moment of actuation of the chronograph that should be eliminated. There are also other applications that require a coupling in a timepiece that are affected by similar problems.
In this context, solutions have been proposed in order to reduce or eliminate the above-mentioned problems. For example, European patent application EP 2 060 958 discloses, within the scope of a coupling for a chronograph mechanism, a gearwheel comprising a toothing of specific form, in particular having teeth having a foot and a head of particular form. In addition, the axis of the coupling and setting wheel is placed, by contrast with the arrangement of a conventional chronograph, over the line between the axes of the seconds wheel and the chronograph wheel, and the shape of the coupling yoke, disposed such as to be adapted to bring said setting wheel into engagement with the chronograph wheel or to distance same, allows to obtain a translation of the coupling and setting wheel during the movement thereof between the two decoupled and coupled positions thereof oriented almost perpendicularly to the circumference of the chronograph wheel. Thus, the coupling and setting wheel does not move in translation along the circumference of the chronograph wheel, which limits the above-mentioned parasitic rotation. This layout, however, requires a complicated toothing on the coupling device setting wheel and increases the production cost. At the same time, the space occupied by this mechanism remains considerable, and the mechanism requires a specific arrangement of the parts thereof relative to one another, which limits the use thereof both for functions other than a chronograph and in extra-flat movements.
As a result, other types of coupling have also been proposed in the past. Amongst others, U.S. Pat. No. 6,773,157 discloses a time correction device comprising a winding stem cooperating on the one hand, as is conventional, with a minutes hand and hours hand correction train, by means of a first correction wheel. On the other hand, the device comprises a second correction wheel, which is mounted on a fixed axis partially having the form of a cone so that the second correction wheel can be inclined about this axis, depending on the position of a control spring controlled by the stem and cooperating with another spring exerting a prestressing force onto the second correction wheel. Depending on its inclination, the second correction wheel may or may not mesh with part of said correction train, and, when it is in the meshing position, the winding stem does not mesh with said first correction wheel. Although this device can, in principle, be used for several applications such as the fast adjustment of the hours hand independently of the minutes hand or for the correction of the date, the mechanism is even more bulky than a conventional coupling and does not lend itself to integration in a flat movement. In addition, the use of a fixed truncated conical axis of rotation in combination with a control of the inclination of the coupling pinion mounted on this axis by a number of springs does not appear to ensure reliable operation.
Further designs using a tilting coupling wheel, either by being mounted on a fixed axis of rotation or by other similar means, are disclosed in documents DD 127 363 and U.S. Pat. No. 413,654. The time correction device according to DD 127 363 comprises a coupling pinion which, under the influence of the winding stem, can tilt about the axis thereof so as to be in contact either with the winding-mechanism wheel or with the time-setting wheel. Due to the fact that the coupling pinion is mounted on a pivoting lever in a cage, it is oriented substantially vertically relative to the winding-mechanism wheel and the time-setting wheel, which directly implies a significant bulk in the height direction. The mechanism is thus unsuitable for integration in extra-flat movements. In addition, this coupling, respectively the corresponding correction device, can only control two functions and therefore is not suitable for high-end timepieces having a number of functions. Document U.S. Pat. No. 413,654 describes a winding and time-setting system which comprises a coupling wheel adapted to tilt about a fixed axis of rotation. This coupling wheel makes it possible to transmit the movement of the winding stem either to the winding-setting wheel or to a wheel of the time-setting train, depending on the inclination of said coupling wheel, which is controlled by the winding stem with the aid of a ring mounted concentrically relative to the coupling wheel and comprising a lip for cooperating with the stem. Again, this device can only control two functions, and the operation of said device does not appear to be reliable, given that the inclined position of the coupling wheel, following the release of the coupling wheel, is not obtained by stress, but by the action of the force of gravity, which changes in accordance with the orientation of the corresponding timepiece.
The solutions of the prior art mentioned above have the common feature, apart from document DD 127 363, which proposes a rather particular arrangement having a coupling pinion mounted substantially vertically relative to the winding wheel and to the time-setting wheel, that the coupling pinion is arranged substantially in the plane of rotation of the entry wheel, for example the seconds wheel or the winding wheel, and the exit wheel, for example the chronograph wheel or the time-setting wheel. In spite of this layout the devices according to these documents do not lend themselves, for the reasons mentioned above, to integration in an extra-flat movement and are often affected by other disadvantages as explained above. Another type of devices according to the prior art is disclosed for example in documents FR 436 356, CH 2 547, EP 0 261 243, and EP 1 288 743. The common feature of these devices is that the entry wheel and the exit wheel are not arranged in the same plane of rotation, but in two different planes, such that the coupling pinion serving as a kinematic connection between these two wheels must be formed by a double pinion, of which one pinion cooperates with the entry wheel and the other pinion with the exit wheel.
For example, document FR 436 356 proposes a device having a double tilting pinion fixed to an inclinable axis perpendicular to the plane of rotation of the entry and exit wheels, arranged in two different planes, the inclination of the axis being caused by the displacement of a spring controlled by a movable part. The device clearly is not suitable for use in an extra-flat movement, and the control of said device does not appear to be very reliable. The document CH 2 547 also discloses a double tilting pinion fixed to an inclinable axis perpendicular to the distant parallel planes of rotation of the entry and exit wheels, the ends of the inclinable axis being fixed in a fork housed rotatably and perpendicularly relative to said axis. This system must have pinions of very small diameter in order to function, but also is unsuitable for integration in an extra-flat movement. Documents EP 0 261 243 and EP 1 288 743 also disclose a double tilting pinion fixed to an inclinable axis perpendicular to the distant planes of rotation of the entry and exit wheels, the inclination of the axis being caused in both cases by the displacement of a movable control member. The latter either carries, according to EP 0 261 243, an end of the inclinable axis, or constrains, according to EP 1 288 743, this end, otherwise mounted freely, by pressure. Similarly to the devices according to documents FR 436 356 and CH 2 547, these devices are not suitable for integration in an extra-flat movement, document EP 0 261 243 also specifying a condition on the minimal length of the inclinable axis so as to allow correct operation of the coupling. These devices in addition can only control a single function, which can be engaged or disengaged.
It must therefore be stated that, in spite of the significant number of pre-existing devices, the solutions of the prior art currently known for providing such a coupling, whether of the type having a coupling pinion in the same plane of rotation as the entry and exit wheels or of the type having a double coupling pinion on account of the distant planes of rotation of the entry and exit wheels, are not entirely satisfactory, are not suitable for certain applications, and cannot be used for any type of movements, in particular are not suitable for extra-flat movements.